The present invention relates to a fuel injection control device for an internal combustion engine. The present invention relates especially to a fuel injection control device for an internal combustion engine of a so-called fuel cylinder injection type which injects the fuel directly to the combustion chamber. More concretely, the present invention relates also to a fuel cylinder injection engine with a the supercharging machine.
The fuel cylinder injection engine with the supercharging machine is disclose in the Japanese Patent Application Laid-Open No. 2000-54894. In the fuel injection control device of this prior art, the fuel spray is divided within the range of the ignition time and the intake stroke when the acceleration is detected, and the fuel injection timing in the later term is set after the middle term of the compression stroke. The combustion gas is supplied to the exhaust side at shorter time after ignition, and high energy is given to the turbine of the turbocharger by making like this. Namely, the response of the turbocharger is improved.
However, it has been understood that the fuel spray is crushed by the pressure of the combustion chamber when the fuel spray is injected to the combustion chamber where pressure was improved by the supercharging machine, the fuel distribution in the center part of the fuel spray rises (in a word, the fuel spray concentrates on a specific part), and there is a tendency that the ignitability of the fuel deteriorates in the technology described in the above-mentioned Japanese Patent Application No. 2000-54894.
Moreover, the fuel is divided into the previous term and the later term of the compression stroke in the middle term of acceleration between the previous term of acceleration of the engine and the later term and injected in the above-mentioned prior art.
However, the total injection time of the fuel injection can do nothing but shorten because the time allowed for the fuel injection in the compression stroke shortens when the engine is comparatively in high loaded condition. Therefore, the problem that the injection in the previous term and the injection in the later term becomes close and the effect of divided injection is lost occurs.
Here, on the assumption of the slow acceleration in the stratification drive area where the previous term injection and the later term injection are continuously occurred (For instance, in the vicinity of 1 ms at the injection interval between the previous term injection and the later term injection), the driving current decreases due to shortage of the charging time of the voltage applied to the fuel injection valve, and injection amount on the later term side might decrease consequentially. The air/fuel ratio becomes lean when the injection amount decreases, and the accidental fire might occur.
Moreover, the power supply line voltage changes, because the electric load always changes by the drive of the auxiliary machine etc. Therefore, it is necessary to detect the change of the power supply line voltage, and to make the exhaust and the operability not influence.
An object of the present invention is to cancel at least one of the above-mentioned problems.
An object of a certain invention is to decrease the exhaust rate of the smoke and the hydrocarbon by preventing the fuel spray from concentrating on a specific part.
Moreover, an object of another invention is to provide a fuel control device suitable for the fuel cylinder injection type engine with the supercharging machine.
In addition, an object of another invention is to expand the stratification drive area by devising the control of the fuel injection valve to do the stable divided injection, and, as a result, to achieve the decrease of the fuel consumption.
It is effective to the fuel cylinder injection engine without the supercharging machine though the present invention is suitable for the fuel cylinder injection type engine with the supercharging machine.
Therefore, the supercharging machine is especially added to the component parts in the invention suitable for the fuel cylinder injection type engine with the supercharging machine.
To solve at least one of the above-mentioned problems, the first invention relates to the internal combustion engine with the supercharging machine where the fuel injection valve for injecting the fuel directly to the combustion chamber is installed. A fuel density control means by which the fuel density of the mixture of the fuel and the air around the sparking plug at the ignition timing under supercharging is controlled to become a suitable density for the ignition is provided in this invention. The center part density of the fuel spray can be prevented from becoming excessive under the supercharging, and the air/fuel ratio around the sparking plug is prevented from becoming excessive according to this configuration. Therefore, the ignitability of the internal combustion engine with the supercharging machine is improved, and the decrease of the amount of the exhaust of the smoke and the unburnt fuel becomes possible.
Concretely, the fuel density control means sprays by dividing an amount of the fuel necessary for one combustion under the supercharging into two times before the timing of the ignition of the sparking plug.
Or, the basic spray form is a cone form, and the slit part where the fuel density is small, for balancing the pressure of the inside and the outside of the cone is formed in the cone spray.
Moreover, at least one of the spray allotment rate and the spray intervals of the divided spray can be adjusted according to the operating state of an engine, for instance, the magnitude of the voltage of the battery.
The second invention relates to the internal combustion engine with the supercharging machine where the fuel injection valve for injecting the fuel directly to the combustion chamber is installed. The fuel density control means by which the fuel density of the mixture of the fuel and the air around the sparking plug at the ignition timing under supercharging is controlled to become a suitable density for the ignition is provided in this invention. Further, the control valve mechanism which supplies the exhaust only to the catalyst by bypassing the exhaust turbocharger for driving the supercharging machine when the engine is started is installed. It is possible to activate the catalyst at the early stage, and to prevent from discharging the more harmful exhaust thing according to this configuration.
To solve at least one above-mentioned problems, the third invention provides with a supercharging machine, a fuel injection valve installed in the combustion chamber, for injecting directly fuel, and a mixture promotion device of the fuel and the air. This mixture promotion device is driven before and after the beginning of fuel injection. The center part density of the fuel spray can be prevented from becoming excessive according to this configuration. The air/fuel ratio around the sparking plug can be prevented from becoming excessive. As a result, the ignitability is improved, and the decrease of the amount of the exhaust of the smoke and the unburnt fuel becomes possible.
It is more effective that an air flow generation mechanism for generating the tumble air flow and/or the swirl one in the cylinder is provided in addition to the third invention. The mixture of the fuel and the air in the cylinder can be effectively done by using the air flow generated at the intake stroke according to this configuration.
In addition, it is effective that the air flow generation mechanism and the divided injection are used together.
To solve at least one of the above-mentioned problems, the fuel injection is controlled to inject the divided fuel two times or more between the intake stroke and the compression stroke, and injection amount (the injection time, the injection pulse width and the fuel pressure) is controlled based on the voltage fluctuation, in the fourth invention.
The touch area to the air of the fuel spray expands by dividing the fuel injection compared with the batch inject, and there is an effect advanced by the mixture of the fuel and the air according to the above-mentioned configuration. In addition, even if the voltage fluctuation is generated between the previous injection and the later injection, the torque change due to the instability of the combustion and the accidental fire due to the decrease of the injection amount can be prevented.
In addition, the frequency of divided injection is decreased or the injection interval is extended when the voltage drop is detected during divided injection. The combustion stability can be maintained by preventing the accidental fire even if the voltage drop is generated while executing divided injection according to this configuration.
To solve at least one of the above-mentioned problems, the fuel spray amount necessary at the cycle of one combustion is injected in twice between the compression stroke and the intake stroke, and the fuel injection valve is driven by substantially the same voltage as the power supply line voltage, in the fifth invention. Because the booster circuit becomes unnecessary, power consumption in the entire electronic equipment of the fuel injection control system can be decreased according to this configuration.
Because at least one of the above-mentioned problems is solved, the fuel spray amount necessary for one combustion is injected in twice between the compression stroke and the intake stroke in the fuel cylinder injection engine with the supercharging machine of the sixth invention. The fuel cylinder injection engine with the supercharging machine which can spark-advance the ignition timing as well as a fuel cylinder injection engine of the natural suction type under the supercharging can be achieved according to this configuration.
Moreover, with regard to the interval between the previous injection and the later injection in the divided injection, the time necessary to charge the coil of the fuel injection valve in the later injection with energy by setting the minimum injection interval. The accidental fire and the torque change due to the decrease in the amount of fuel injection can be prevented according to this configuration.
To solve at least one of the above-mentioned problems, it is also possible to provide the mechanism in which the fuel and the air are premixed, and the mixture is injected in the cylinder as an example of the application of the third invention in the sixth invention.
At this time, the compression natural gas can be used as the mixture means. Only the inject of the fuel or the compression natural gas can become possible according to this configuration. Therefore, the engine with the two or more fuel systems which can use both the liquid fuel and the gaseous fuel can be provided.
It is possible to perform the stratification operation to the higher engine speed by using the injection valve having the spray with a long spray travel, in a word, strong penetration (the long penetration spray) as an spray form of the fuel injection valve used for the spray control device of the third invention.
Moreover, to solve at least one of the above-mentioned problems, an eighth invention is provided with a mechanism for making the time of opening and shutting of suction and exhaust valve changeable, and a means for introducing the combustion gas from the exhaust port to the combustion chamber (thereafter, call internal EGR), and generating a weak swirl stream in the cylinder besides the air flow supplied from the suction port. It is effective to generate the gas flow in which the combustion gas flows along the cylinder wall by said weak swirl stream
Concretely, the opening and shutting time changeable control of suction and exhaust valve spark-advances the close time in the one side of the exhaust valve, spark-delays the open time of the exhaust valve and an suction valve in the diagonal direction, and provides the phase difference at right and left opening and shutting valve time of the suction and exhaust valve. As a result, the swirl stream is generated.
Moreover, the phase difference is given in advance to the right and the left valves to shift smoothly from the high revolution drive area to the low revolution drive area.
In addition, the valve overlap is controlled by an opening and shutting time changeable control of suction and exhaust valve, and the opening and shutting valve time changeable control of two stages is executed, in which the opening and shutting valve time of the suction valve in one side is made changeable as the first stage, and the valve lift of the exhaust valve is increased as the second stage when the internal EGR is increased next.
In addition, it is effective that the swirl guide part is installed on the piston crown face as a means for generating the gas flow along the cylinder wall.